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mutation-testing

Introduce code mutations and measure kill rate with Stryker and Jest.

Updated Jun 15, 2026
Search Tags:#test automation#mutation testing#test suite#test effectiveness#kill rate
One-click install
npx skills add https://github.com/CENKSSS/valocase-backend --skill mutation-testing-cenksss
Or copy as Structured Prompt for Agent▼
Please help me install this Agent Skill.
Skill: mutation-testing
Source: https://github.com/CENKSSS/valocase-backend/tree/main/.claude/skills/mutation-testing
Command: npx skills add https://github.com/CENKSSS/valocase-backend --skill mutation-testing-cenksss

SYSTEM DOCUMENTATION & REQUIREMENTS

💡 This Skill requires @stryker-mutator/core, @stryker-mutator/jest-runner, jest, node, and includes scripts (resource) and references (resource) and assets (resource) components.

What problem does it solve?

This Skill helps evaluate the effectiveness of a test suite by introducing code mutations and measuring the kill rate, thereby identifying weak tests and proving test effectiveness.

Core Features & Use Cases

  • Mutation Testing: Introduces code mutations to evaluate test suite effectiveness.
  • Kill Rate Measurement: Measures the rate at which mutations are killed by tests.
  • Identify Weak Tests: Helps identify tests that do not effectively catch mutations.
  • Use Case: Before a critical release, use this Skill to ensure that your test suite is robust and can effectively catch bugs.

Quick Start

Run the mutation-testing skill to analyze your test suite and get a mutation score and a list of surviving mutants.

Frequently Asked Questions about mutation-testing

High-intent search queries and answers about installing and using this skill.

FAQPage Schema
What is mutation testing and how does it measure test suite effectiveness?▼

Mutation testing evaluates test suite effectiveness by introducing code mutations and measuring the kill rate to identify weak tests. It mutates source code to check if the existing test suite catches the introduced bugs, proving test robustness.

How do I identify weak tests in my Jest test suite before a critical release?▼

To identify weak tests in your Jest test suite, run a mutation testing analysis to introduce code mutations and measure the kill rate. This process highlights tests that fail to catch mutations, allowing you to improve test suite robustness before release.

Does mutation testing with Stryker work with Jest and Node.js?▼

Yes, mutation testing with Stryker works with Jest and Node.js. The analysis requires Stryker for mutation execution, Jest for running the test suite, and Node.js for the environment, ensuring accurate measurement of test effectiveness and kill rate.

What is a good mutation score and how do I improve my test suite's kill rate?▼

A high mutation score indicates a robust test suite. To improve your test suite's kill rate, review the surviving mutants report generated by mutation testing, identify the corresponding weak tests, and add assertions to catch the unhandled code mutations.

What are the limitations of using Stryker for mutation testing?▼

The primary limitation of using Stryker for mutation testing is performance overhead, as introducing code mutations and executing the test suite repeatedly for kill rate measurement can be time-consuming. It requires a properly configured Jest and Node.js environment.

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